# Vectorization of nested for loop

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Ilaria on 12 Oct 2023
Edited: Ilaria on 8 Dec 2023
Hello,
I am trying to vectorise a piece of code. The code is the following:
main_calc=zeros(N,length(time)); %initialize main calculation
for wall_send=1:length(6) %sending wall
for send=1+lenght(wall_send):lenght(wall_send+1) %elements on the sending wall
for wall_rec=1:length(6) %receiving wall
for rec=1+lenght(wall_send):length(wall_send+1) %elements of receiving wall
main_calc(rec,time_step_ij)=main_calc(rec,time_step_ij)+previous_calc(send,time_step_ij); %new calc
end
end
end
end
previous_calc=main_calc; %update
How do I vectorize the above code?
Thank you
Rena Berman on 5 Dec 2023

Sulaymon Eshkabilov on 12 Oct 2023
I don't think what you are doing is a vectorization. Here is a simple demo of vectorization :
% Loop
x = linspace(0, 2*pi);
y = linspace(-pi, pi);
Z = zeros(numel(x), numel(y));
for ii = 1:numel(x)
for jj=1:numel(y)
Z(ii,jj) = sin(x(ii))+cos(y(jj));
end
end
figure(1)
mesh(Z)
title('Computed with a loop')
% Vectorization
x = linspace(0, 2*pi);
y = linspace(-pi, pi);
[X, Y] = meshgrid(x,y);
Z = sin(X)+cos(Y);
figure(2)
mesh(Z')
title('Computed with a vectorization')
Ilaria on 16 Oct 2023
i am not sure this does help me. What should I do in my case?